1. Field of the Invention
The present invention relates to initiation systems, and more particularly to an ac initiation system using three ac transmission signals interlocked for safety by frequency, phase and power discrimination.
2. Description of the Prior Art
The use of electroexplosive devices (EEDs) for initiation and control of missile systems is limited to only two acceptable techniques. One is the low-voltage hot-wire primary ordnance EED initiator incorporating an electromechanical safe and arm (S&A) device. The other is a high-voltage exploding bridgewire (EBW) secondary-ordnance EED initiator incorporating a safety spark-gap device. Both of these systems require parallel redundant channels to achieve advanced missile reliability requirements. This tends to increase missile volume, weight, and cost.
The hot-wire EED system uses primary ordnance and, therefore, requires inclusion of an S&A device. The electromechanical S&A device maintains the EED out of alignment for safing and moves the EED inline with the ordnance event for arming. The S&A requires EED mechanical movement and retention in all operational environments, and places limits on the reliability per initiation channel and on the weight and volume. The hot-wire EEDs have demonstrated high reliability; however, because of electrical power source limitations, an EED high-order output requires the use of primary ordnance.
The high-voltage EBW secondary-ordnance EED represents an attempt to eliminate the limiting effects of low-voltage primary ordnance and the S&A device used in the initiation and control of missile systems. The higher voltage power source permits secondary-ordnance initiation, thus eliminating the need for an S&A device. The high-voltage EED system includes a hold-off spark gap, and achieves a reliability higher than that of the low-voltage system. However, special packaging techniques are required to preclude arcing at high altitude, and, for complex systems, the spark gap reliability requires redundancy, which affects volume. The high-voltage EBW system also has difficulty in satisfying vulnerability and hardening concerns.
Therefore, it is desired to provide sufficient electrical power for hot-wire secondary high-order ordnance EEDs with such a high reliability that redundancy is not necessary.